title: The hydrogen-bonding transition and isotope-dependent negative thermal expansion in H3Co(CN)6.
abstract: We investigate the structures of H(3)Co(CN)(6) and D(3)Co(CN)(6) and their temperature dependence using a combination of advanced neutron and x-ray diffraction techniques. Lattice parameter refinements show marked temperature- and isotope-dependent effects in the thermal expansion behaviour. Reverse Monte Carlo modelling of neutron total scattering data characterizes the distribution of D atom positions in the deuterated compound; analysis of these distributions reveals that the two N-H/D bonds become increasingly different with increasing temperature, suggesting a mechanism for the observed thermal expansion anomalies. We discuss these results in the context of the previous crystallographic, spectroscopic and theoretical results for H(3)Co(CN)(6) and 'super-short' N···H···N systems in general.
authors.affiliation: ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, UK. david.keen@stfc.ac.uk
authors.forename: David A
authors.initials: DA
authors.lastname: Keen
authors.forename: Martin T
authors.initials: MT
authors.lastname: Dove
authors.forename: John S O
authors.initials: JS
authors.lastname: Evans
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Goodwin
authors.forename: Lars
authors.initials: L
authors.lastname: Peters
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Tucker
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D003198:Computer Simulation; D003486:Cyanides / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D015394:Molecular Structure; D009010:Monte Carlo Method; D033363:Neutron Diffraction
chemical_list: D003486:Cyanides; D003035:Cobalt; D006859:Hydrogen; D003903:Deuterium